1. Field of the Invention
The present invention relates to a method for visually observing vibration mode due to vibration occured at structures or materials.
2. Description of the Prior Art
It is very important to know vibration mode when structures or materials are vibrated in designing machines, structures, and etc.
Conventionally, there has been no method for directly detecting vibration mode. For observation of vibration mode generated in a structure, in a conventional method, so-called multi-point observation method has been used, wherein acceleration sensors are provided on several points of the surface of the structure to be measured. In this conventional method, measured values obtained from each measuring point have collected as data. The data have been analysed to know vibration mode on the vibrating faces by using mode analysis.
In the above-mentioned conventional method, there have been troublesome defects in observing operation such that many acceleration sensors have been required; a large numeral values has been required due to repeated measurement at the respective points; provision of sensors and cable wiring have been required to obtain data.
On the other hand, there has been known FEM (Finite Element Method) as a method in which vibration mode has been measured by calculation. However, the FEM is mere simulation and requires calculation of large amount of numeral values. In the FEM, there have been many cases where the obtained result has not been always agreed with the actual vibration mode which occurs at the structure to be measured.